A problem that occurs during ink-jet printing is that immediately after graphic information such as text, for example, has been printed on a record sheet, a certain period of time must pass before the graphic information just printed is sufficiently smudge-resistant so that the printed side of the record sheet can contact other objects without smudging the print. This is particularly true when a nonpenetrating ink is used. While in principle it is possible to decrease the drying time by using a heater and/or blower, such devices add to the cost of the printer and, because of their high power consumption, are not suitable for small battery-operated ink-jet printers. Hence, if supplemental drying aids are dispensed with, it is necessary to prevent the printed graphic information from contacting other objects while the record sheet that has just been printed is conveyed from the printing zone to an output area.
This task might be accomplished if conveyor rolls used to transport the record sheet were to make contact therewith only near the margins. However, given a sheet having a printing width of 8 inches, and allowing for tolerances, there would only remain available a few tenths of a millimeter at the edge of an A4 sheet that could be used for transportation. Otherwise, the available printing width would have to be reduced. Alternatively, if a pin feed were used to move the record sheet, smudging would be confined to individual points but would not be prevented altogether. Other possible methods for transporting the record sheet into the output area include: holding the back of the sheet by electrostatic forces or by a vacuum, as described in U.S. Pat. No. 4,207,579, for example; moving the sheet by conveying air; providing additional acceleration of the advancing sheet at the end of the printing process; or utilizing gravity to move the sheet to the output position. However, these methods either involve a considerable expenditure in terms of their construction and power consumption, or they do not reliably convey the print medium to the output area, especially when different weights of paper are used.
Thus, the problem with the prior art is that there is no apparatus for the transportation of record sheets in an ink-jet printer in which smudging of the printed graphic information is prevented, and which has a design and sufficiently low power consumption that makes it particularly suitable for small battery-operated ink-jet printers, and furthermore which reliably conveys the record sheets to an output area.